ISIS militants have begun destroying the ruins of the ancient city of Hatra in Iraq, Kurdish sources say.

Hatra was founded in the days of the Parthian Empire over 2,000 years ago and is a UNESCO world heritage site.

Earlier this week, ISIS militants began bulldozing the nearby ruins of the Assyrian city of Nimrud.

ISIS, which controls large areas of Iraq and Syria, says shrines and statues are “false idols” that have to be smashed.

It not yet clear how extensive any damage might have been.

Hatra, located about 68 miles south-west of Mosul, was a fortified city that withstood invasions by the Romans thanks to its thick walls reinforced by towers.

Said Mamuzini, a Kurdistan Democratic Party (KDP) local official, told Kurdish media that IS militants had started destroying the site.

“The city of Hatra is very big and many artifacts of that era were protected inside the site,” he said, adding that the militants had already taken away gold and silver.

There is no independent confirmation of the destruction.

Reports of the bulldozer attack in Nimrud, an Assyrian city founded in the 13th Century BC, emerged on March 5.

On March 6, UNESCO head Irina Bokova condemned the “cultural cleansing” in Iraq as a “war crime”.

“There is absolutely no political or religious justification for the destruction of humanity’s cultural heritage.”

The Parthian Empire was a major political and cultural force in ancient Iran. At the height of its power in the second century AD, it extended from modern-day Pakistan to Syria.

Hatra later flourished under Arab rulers, and became a major trading-post on the Silk Road across the Asian continent.